Vertical feed mixers have been used in agriculture for many years. Vertical mixers process forages and commodities of all types of feed for livestock. Vertical mixers include a tub containing one or more vertical augers. These augers can have knives mounted on their flights such that when the augers rotate, the knives will cut the forage and the augers will process and blend the components within the tub. The augers are typically driven using power from the PTO of a tractor or other type of motor vehicle having a suitable PTO system. Known designs of vertical mixers use automatic transmissions or 2- or 3-speed manual gearboxes in the driveline between the PTO and the augers in the vertical mixer.
The use of such transmissions or gearboxes is prone to failures due to the high start-up torque required to engage large mixers. In order to reduce the cost of the mixer, gearboxes are used that are not rated for the amount of horsepower and duty cycles that large mixers require. The operator of the mixer is required to shift gears on the gearbox while on the tractor seat using a shift cable. To do so requires that the PTO be disengaged and all driveline movement stopped so that gears can be shifted. On larger mixers, this process often adds too much time to feeding schedules for most operators. Operator misuse of the system often leads to component failures. The use of automatic transmissions solves the manual gearbox shifting problems but most suffer from mounting, cooling and reliability issues. Repairs to automatic transmissions are expensive.